1. Field of the Invention
The invention relates to an optical system including an optical amplifier having a laser active substance and a pump laser, and having a second laser producing light which can be amplified in the optical amplifier.
2. Background Information
The term "optical system" is hereinafter understood to mean a combination of various optical devices such as, for example, lasers, light waveguides, fiber-optic amplifiers, which coact with one another while possibly being disposed far removed from one another.
The article in "ECOC'89, Fifteenth European Conference on Optical Communication", Sep. 10-14, 1989, Gothenburg, Sweden, Proceedings, Vol. 1, Regular Papers TuA5-7, pages 86-89, discloses such an optical system. The system is an optical communication transmission system. The laser active substance employed in the fiber-optic amplifier is composed of Er.sup.3+ ions which are included as doping agent in a section of a light waveguide. The first laser generating the pump light is a Kr.sup.3+ gas laser and the wavelength of the pump light is 530.9 nm. The second laser is disposed far removed from the fiber-optic amplifier. The light it emits has a wavelength of 1537 nm and is amplified by the fiber-optic amplifier. A light waveguide of a length of more than 70 km serves to couple the light generated by the second laser into the fiber-optic amplifier.
The second laser generates light whose intensity is modulated with the electrical communication signal to be transmitted. The laser is therefore called the transmitting laser of the optical communication transmission system.
For the present invention, the modulation of the light generated by the second laser and several special characteristics of the prior art optical system, for example the spatial separation of its various components, are insignificant. The only important factor is that the system includes a fiber-optic amplifier equipped with a pump laser and that a second laser is provided whose output light is coupled into the fiber-optic amplifier and is amplified therein.